Normally when you create any report in Access thru' Wizard, you might have a field for percentage. That field's value (in control source) would be:

=Sum([fieldname])/([fieldname Grand Total Sum])

Now, I need to change the fieldname. I could change the fieldname but how could I change the percentage formula? If I change the fieldname in that formula, it does not work!

Any Idea how to do that, or I have to create a fresh report all again?